1. Field of the Invention
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus in which even when liquid ejecting portions are arrayed in a staggered manner in the arrangement direction of the liquid ejecting portions, the impacted dot rows are arranged on a substantially straight line.
2. Description of the Related Art
When attempting to realize a nozzle (liquid ejecting portion having a nozzle) row at as fine pitch as possible in a liquid ejecting apparatus or the like, when nozzles are arranged along one straight line, the distance between adjacent nozzles and the nozzle pitch become equal to each other. In contrast, when the nozzles are sequentially arranged in a staggered fashion along a plurality of straight lines, the distance between the nozzles can be made larger than the nozzle pitch.
FIGS. 22A and 22B illustrate this state. FIG. 22A illustrates a case where the nozzles are arrayed in a straight line, and FIG. 22B illustrates a case where the nozzles are arrayed in a staggered manner. In FIG. 22B, there are two nozzle rows R1 and R2. At this time, the distance between the nozzle rows R1 and R2 is δ. Further, the pitch in the arrangement direction of the nozzles is P that is the same as the pitch in FIG. 22A.
Accordingly, while the distance between the centers of the nozzles (nozzle pitch) is P in FIG. 22A, in the case of FIG. 22B, the distance between the centers of the adjacent nozzles is “√{square root over ( )}(P2+δ2)” and thus can be made longer than that in the case of FIG. 22A.
This is also reflected in impact dot rows indicated at the bottom of FIGS. 22A and 22B. That is, normally, a dot formed as an ink droplet impacts on a recording medium remains as a substantially circular dot and, at least in the case of an ordinary inkjet head, the amount of the droplet is suitably selected so that the diameter thereof becomes substantially equal to the recording pitch. Therefore, in the array of FIG. 22A, adjacent dots are substantially in contact with each other. In contrast, in the case of FIG. 22B, the adjacent dots are arranged in a staggered array, thus leaving a gap therebetween.
Further, there have been disclosed various methods aimed at making the flight direction of ink droplets ejected from the nozzles coincide with or close to the directing of the normal passing through the center of each nozzle.
For example, there have been disclosed a method in which, as disclosed in Japanese Patent No. 2720989, the centerline of each nozzle is offset to the ink supply side with respect to the center of the resistor, a method in which, as disclosed in Japanese Unexamined Paten Application Publication No. 2001-10056, the centerline of the nozzle is offset in the opposite direction, that is, the centerline of the nozzle is placed toward the rear side of the ink liquid chamber with respect to the center of the ink liquid chamber, and the like (Note that as mentioned above, the direction in which the center of the nozzle is offset is opposite between Japanese Patent No. 2720989 and Japanese Unexamined Paten Application Publication No. 2000-110056).